Xerographic or electrophotographic image forming methods and systems are used in marking or imaging devices such as copiers, scanners, fax machines, laser printers, multifunction devices, and the like. A photoreceptor of the imaging devices can have a charge transport layer (CTL) that can carry the charge that determines toner placement on a substrate to be copied or printed. Over the lifecycle of the imaging device and corresponding photoreceptor, the CTL can deplete and reduce in thickness, which can cause the photoreceptor to be more susceptible to field breakdown within the CTL. The field breakdown can lead to spot defects known as charge depleted spots (CDS). If an imaging device has an issue with CDS, the substrate outputs produced by the imaging device can have noticeable spots that reduce the accuracy and quality of the prints.
To prevent the occurrence of CDS defects in customer prints, a counter with a programmed or estimated life counter replacement value can be used to trigger the end-of-life and/or replacement for the photoreceptor. For example, imaging devices can have photoreceptors, charging devices, and/or cleaning blades that can be packaged together in a subassembly that can be customer- or service engineer-replaceable. A replacement interval of the subassemblies can drive a large percentage of a run cost of the imaging device, and the life counter replacement value of the photoreceptor can be a driving element for defining a life of the subassemblies. In particular, a population reliability model can be used to set the life counter replacement value for the photoreceptor and the corresponding subassembly, such as, for example, using a “B10” life model. If the imaging device reaches the life counter replacement value, the imaging device can stop printing and the subassembly can be deemed to require replacement. For example, the imagine device can stop printing and can be shipped to a replacement center for replacement.
Because the life counter replacement value of the photoreceptor is affected by a number of customer usage factors, such as, for example, area coverage, environmental conditions, developer age, and job length, the estimated remaining useful life of the photoreceptor may not be accurate. As a result, the photoreceptor may fail, and CDS defects may occur, before the estimated life limit is reached. Further, the photoreceptor may have remaining workable cycles when the estimated life limit is reached.
A need, therefore, exists for systems and methods that allow for a more accurate photoreceptor life limit measurement. Further, a need exists for systems and methods for reducing costs associated with estimated life limits.